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A140615 Primes of the form 13x^2+6xy+21y^2. 2

%I

%S 13,61,109,277,349,373,541,613,733,853,877,997,1069,1117,1381,1429,

%T 1597,1669,1693,1789,1861,1933,2053,2221,2389,2437,2749,2917,3109,

%U 3181,3229,3253,3373,3517,3541,3637,3709,4021,4549,4597,4813,4861

%N Primes of the form 13x^2+6xy+21y^2.

%C Discriminant=-1056. Also primes of the form 13x^2+2xy+61y^2.

%C In base 12, the sequence is 11, 51, 91, 1E1, 251, 271, 391, 431, 511, 5E1, 611, 6E1, 751, 791, 971, 9E1, E11, E71, E91, 1051, 10E1, 1151, 1231, 1351, 1471, 14E1, 1711, 1831, 1971, 1X11, 1X51, 1X71, 1E51, 2051, 2071, 2131, 2191, 23E1, 2771, 27E1, 2951, 2991, where X is 10 and E is 11. Moreover, the discriminant is -740. - _Walter Kehowski_, May 31 2008

%H Vincenzo Librandi and Ray Chandler, <a href="/A140615/b140615.txt">Table of n, a(n) for n = 1..10000</a> [First 1000 terms from Vincenzo Librandi]

%H N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)

%t Union[QuadPrimes2[13, 6, 21, 10000], QuadPrimes2[13, -6, 21, 10000]] (* see A106856 *)

%Y Cf. A140633.

%K nonn,easy

%O 1,1

%A _T. D. Noe_, May 19 2008

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Last modified May 7 07:55 EDT 2021. Contains 343636 sequences. (Running on oeis4.)